I've faced some strange behavior in our SCOM environment. After a switch maintenance, we've lost a LAN connection for more than 2 hours and our management server was hit hard with all alerts generated from every device. After we restore the LAN connection, the management server is filled with event ID 20002 : "A device at IP xx.x..xx.xx:58245 attempted to connect but could not be authenticated, and was rejected." and it's grayed out.
All except few clients agents are also grayed out.
I got the below on the client Ops Manager log
Event ID: 21006
The OpsMgr Connector could not connect to RMS:5723. The error code is 10061L(No connection could be made because the target machine actively refused it.). Please verify there is network connectivity, the server is running and has registered it's listening port, and there are no firewalls blocking traffic to the destination.
I tried to flush the RMS and many clients but no luck. Also checked the there's no firewall which blocks the traffic between the RMS and the clients.